class ActionDispatch::Cookies::UpgradeLegacyEncryptedCookieJar

:nodoc:
encrypts and re-saves them using the new key generator to provide a smooth upgrade path.
are both set. It reads legacy cookies signed with the old dummy key generator and
instead of EncryptedCookieJar if secrets.secret_token and secrets.secret_key_base
UpgradeLegacyEncryptedCookieJar is used by ActionDispatch::Session::CookieStore